1. Field of Invention
The invention relates to a sewing machine capable of embroidering, specifically to a sewing machine that subtracts colors included in color display data and generates a subtractive color display data, then writes the subtractive color data into a non-volatile storing medium.
2. Description of Related Art
Conventionally, in an electronically-controlled sewing machine capable of embroidering on a work cloth (hereinafter referred to as an embroidery sewing machine), pattern data for various types of embroidery patterns are stored in a ROM provided in the sewing machine or in a ROM of a ROM card, which is removably inserted into the embroidery sewing machine. A desired embroidery pattern is selected from the various embroidery patterns stored in the ROM. Based on sewing data included in the selected pattern data, an embroidery frame is controlled to move back/forth and right/left, and a needle (a needle bar) moving up and down and a rotary hook are also controlled their movements, and thus the embroidery pattern is embroidered on a work cloth held by the embroidery frame.
Further, the embroidery sewing machine is generally provided with a display. A selected embroidery pattern is displayed on the display based on display data included in pattern data of the selected embroidery pattern, so that an operator confirms the selected embroidery pattern. Further, by performing key operations with editing keys, one or a plurality of embroidery patterns can be edited (e.g., changing the arrangement, enlargement/reduction, or rotation of the pattern) in a pattern display area that corresponds to the embroidery frame.
An embroidery sewing machine in which the display data and the sewing data are rewritably stored in a nonvolatile storing medium, such as a flash memory, has come into practical use, so that once a selected/edited embroidery pattern is set, it can be sewn without selecting/editing it again. In such an embroidery machine, the embroidery pattern is confirmed by displaying the embroidery pattern based on display data stored in the nonvolatile storing medium. When the embroidery pattern is determined as the embroidery pattern to be sewn, the sewing operation of the embroidery pattern can be executed based on sewing data stored in the nonvolatile storing medium.
Recently, there is an embroidery sewing machine that is provided with a color display to display an embroidery pattern in actual colors when the embroidery pattern is colored.
In the embroidery sewing machine that displays the embroidery pattern on the display in color, the data amount for the color display data becomes enormous. For example, the data amount of one dot for displaying the embroidery pattern in black and white is one bit. When the embroidery pattern is displayed in 256 colors, the data amount of one dot requires one byte. Further, when the embroidery pattern is displayed in 640 million colors, the data amount of one dot requires two bytes. Actually, thousands of thread colors can be used for embroidering, so that one dot is expressed by one byte or more of the data.
Therefore, the color display data having the enormous amounts of data has to be stored in the nonvolatile storing medium. Accordingly, in order to store certain amounts of the selected/edited embroidery data in the nonvolatile storing medium, the storage capacity of the nonvolatile storing medium needs to be made large, so that the manufacturing costs may increase.
In another conventional embroidery sewing machine that displays the embroidery pattern on the display in black and white, the data amount of the display data is small even when the pattern data of the embroidery pattern is stored in the nonvolatile storing medium, so that the storage amount of the nonvolatile storing medium does not need to be enormous. However, the selected/edited embroidery data can not be displayed on the display in color, so that the embroidery pattern can not be confirmed in the actual colors. Accordingly, it is difficult for an operator to image a finished embroidery pattern.